Adding wiring for under cabinet lights from a three way switch

Hello,

Just joined this chatroom to find an answer to an electrical situation that I have.
First, I'm retired and a pretty good "handyman" and have a resonable understanding of electrical. But, by no means a professional so a simple explaination might help.
I have a pretty simple setup in my kitchen/dinning room with a three way switch at one end of the kitchen to control overhead lighting and the same at the other end of the dinning room that's also a three way. Next to the cabinets (in the middle of both kitchen and dinning room) is the other switch.
I want to add under and over cabinet lights in that switch. In other words, have the existing light switch for kitchen lights (#1), existing light switch for dinning room (#2)......then add over counter (#3), and under counter (#4).
I have four Romex wires coming into the existing box.....#1 is 14/2, #2 is 14/3, #3 is 14/2 and #4 is 14/3. I'm sure you guys will know the wiring for the existing switches so I won't go into that, my question is where do I "steal" the power to add two runs of Romex? One for the upper lights and one for the under the cabinet lights.
Sorry for the long question and thanks in advance for your response. All of you professionals do a great service with these kind of blogs.
Thanks again,
Dale